OBJECTIVES: (1) To search for viruses which play an etiological role in the syndrome of acute infectious non-bacterial gastroenteritis of infants, children, and adults; (2) to cultivate (in vitro) the viral agents of acute infectious nonbacterial gastroenteritis; (3) to study the biophysical, immunological and epidemiological characteristics of such agents; (4) to reproduce the syndrome experimentally for the purpose of a) studying the pathophysiological and immunological responses of the host, and b) assaying the infectivity of viruses such as reovirus-like agents and the Norwalk and Norwalk-like agents: (5) to develop effective immunoprophylaxis for the viruses of acute, infectious, nonbacterial gastroenteritis; (6) to develop efficient and sensitive assays for a) detection of the viral and bacterial agents associated with gastroenteritis and b) antibodies to these pathogens. BIBLIOGRAPHIC REFERENCES: Kapikian, A.Z., Kim, H.W., Wyatt, R.G., Cline, W.L., Chanock, R.M., Parrott, R.H., Arrobio, J.A., Brandt, C.D., Rodriguez, W.J., Kalica, A.R., VanKirk, D.H.: Studies with the Human Reovirus-Like Agent of Infantile Gastroenteritis. Report No. 1 of the WHO collaboratory Centre for Collection and Evaluation of Data on Comparative Virology: 191-206, 1976. Thornhill, T.S., Wyatt, R.G., Kalica, A.R., Dolin, R., Chanock, R.M., and Kapikian, A.Z.: Detection by Immune Electron Microscopy of 26- to 27-nm Virus-Like Particles Associated with Two Family Outbreaks of Gastroenteritis. J. Infect. Dis. 135: 20-27, 1977.